1. Field of the Invention
The present invention relates to an adjustable torque wrench, and more particularly to an adjustable torque wrench having a lock device for lock the adjustable torque wrench and for preventing the adjustable torque wrench from being further adjusted or rotated after the adjustable torque wrench has been adjusted to the required driving torque.
2. Description of the Prior Art
U.S. Pat. No. 4,870,879 to Shieh discloses a typical adjustable torque wrench including a ratchet arm received in a shank, a spring and a sleeve engaged with the ratchet arm via a roller seat and a roller, and a knob coupled to the spring for adjusting the biasing force of the spring against the ratchet arm. However, the knob may not be locked and may be rotated or driven inadvertently during the operation of the adjustable torque wrench.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional adjustable torque wrenches.
The primary objective of the present invention is to provide an adjustable torque wrench including a lock device for lock the adjustable torque wrench and for preventing the adjustable torque wrench from being further adjusted after the adjustable torque wrench has been adjusted to the required driving torque.
In accordance with one aspect of the invention, there is provided an adjustable torque wrench comprising a shank including a first end and a second end, a driving head including a ratchet arm received in the first end of the shank, a follower received in the second end of the shank, a spring engaged between the follower and the ratchet arm to apply a spring biasing force against the ratchet arm, means for moving the follower relative to the spring to adjust the spring biasing force of the spring against the ratchet arm, and means for locking the follower to the shank and to prevent the follower from moving relative to the shank.
The moving means includes a handle threaded onto the second end of the shank, and means for guiding the follower to slide relative to the shank and to prevent the follower from rotating relative to the shank, the shank is rotated relative to the handle by the follower in order to move and to adjust the follower relative to the shank when the follower and thus the shank are rotated relative to the handle.
The guiding means includes at least one longitudinal groove formed in the shank, and a pin engaged through the follower and slidably engaged in the longitudinal groove of the shank.
A device is further provided for adjusting the follower relative to the handle and includes a lock fastener threaded to the handle and engaged with the follower, the follower is moved and adjusted relative to the handle when the lock fastener is rotated and threaded relative to the handle.
A lock nut is further threaded onto the lock fastener and selectively engaged with the handle in order to lock the lock fastener to the handle.
A knob is further provided and secured to the follower in order to rotate the follower relative to the handle. The locking means includes a control ferrule engaged on the knob and selectively engaged onto the handle in order to lock the knob to the handle and to prevent the knob from being rotated relative to the handle.
The handle includes at least one longitudinal tooth formed thereon, the knob includes at least one longitudinal tooth formed thereon, the control ferrule includes at least one longitudinal tooth formed thereon and slidably engaged with the longitudinal teeth of the handle and the knob in order to prevent the knob from being rotated relative to the handle when the control ferrule is engaged with the handle.
A device is further provided for retaining the control ferrule to the knob and includes a spring-biased projection provided in the knob and engaged with the control ferrule to secure the control ferrule to the knob.
Further objectives and advantages of the present invention will become apparent from a careful reading of a detailed description provided hereinbelow, with appropriate reference to accompanying drawings.